1. Field of the Invention
This invention relates to a paper web threading apparatus for threading a paper web through a paper web processing or handling machine such as, for example, a rotary printing press, and more particularly to a paper web threading apparatus for threading a paper web through a paper web threading path in the machine by moving a paper web threading member of non-endless type to which the paper web is secured on and along a guide member provided along the path.
2. Description of the Prior Art
Prior art apparatuses for threading a paper web through a paper web threading path in a paper web processing machine by moving a paper web threading member to which the paper web is secured along a guide member provided along the path are disclosed, for example, in Japanese Patent Publication No. HEI-2-30978, Japanese Laid-Open Patent Application No. HEI-2-80249 and Federal Republic of Germany Patent No. 22 41 127, etc.
In the paper web threading apparatuses shown in these publications, guide members are provided along paper web threading paths extending from paper supply sections of a rotary printing press which is a paper web processing machine through printing sections to folding sections, and paper web threading members are arranged to run on and along the guide members, and each of the guide members being partially cut away at appropriate places to install driving means for moving the paper web threading member thereon. And, a paper web retaining member connected to the paper web threading member at an appropriate place thereof is projected to the side of the paper web threading path, and a paper web is secured to the paper web retaining member. The arrangement is made such that when the paper web threading member is driven by the driving means so as to move along the guide member with one end thereof located at the leading end thereof the paper web can be threaded through a predetermined paper web threading path.
In the above-mentioned paper web threading apparatuses, to achieve stable movement of the paper web threading member along the guide member, it is necessary for the paper web threading member to have such a degree of rigidity as it is not bent by a frictional resistance between itself and the guide member. Further, since the paper web threading paths in the paper web processing machine are usually bent in complicated manner and the curves of the paths have relatively small diameters, the guide members provided along such paper web threading paths are also formed to be bent at relatively small diameters. Therefore, to achieve stable movement of the paper web threading member along the guide member, it is necessary for the paper web threading member to possess such a degree of flexibility as it may be bent in accordance with the bends of the guide member. Therefore, paper web threading members are formed so as to possess the above-mentioned two characteristic properties.
Whilst, in the above-mentioned paper web threading apparatuses, in case, for example, a foreign matter intrudes into the guide member or a foreign matter is left on or near the guide member for some reason, it impedes the movement of the paper web threading member along the guide member and sometimes stops the paper web threading member. However, since the paper web threading member is driven by driver means so as to be sent out from behind, even when the movement of the paper web threading member is stopped, the driver means still functions to send out or forward the portion of the paper web threading member behind the position where it is stopped.
As a result, in case the paper web threading member is relatively flexible, it is bent or deformed inside the guide member between the position where it is stopped and the driving means, and is damaged finally, and further the guide member is deformed or damaged, or in case the paper web threading member is relatively rigid, the driving means is subjected to an overloading and damaged sometimes.